Ask Pablo: What Impact Will The Volcano In Iceland Have On Climate Change?

Image Source: PlasmastikDear Pablo: What impact will the volcano in Iceland have on climate change?

The short answer is: none. While "global warming" is a measured variance that is caused by both human and natural contributions to the greenhouse effect, the term "climate change" refers specifically to "a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere and which is in addition to natural climate variability observed over comparable time periods" (UNFCCC/a>, Article 1). So by definition, a naturally occurring volcanic eruption cannot contribute to climate change. But what impact will a volcanic eruption have on global warming?Greenhouse Gas Emissions From VolcanoesAccording to the U.S. Geological Survey (USGS), all of the planet's volcanoes are responsible for about 200 million tons of carbon dioxide (CO2) each year. To put this into perspective, the US EPA estimates that global greenhouse gas emissions from human activities totaled 28 trillion metric tons in 2006. In fact, the combined 2008 greenhouse gas emissions of oil company Chevron and power company AEP exceeded the greenhouse gas emissions from volcanoes in that year. In addition, the current volcanic eruptions in Iceland are considered relatively small and are probably only resulting in around one million metric tons of greenhouse gas emissions.

Annual volcanic greenhouse gas emissions may only equal 0.7% of anthropogenic (human-caused) greenhouse gas emissions but every bit counts, right? Sure, if we could somehow stop volcanoes from erupting it would reduce the addition of greenhouse gasses to the atmosphere, but that would be impossible. Besides, volcanic activity has been a constant component of the natural carbon cycle for a very long time. CO2 that spews from a volcano today will soon be absorbed by a plant. That plant will eventually die and add much of its carbon to the soil. Carbon from plant and animal sources eventually find its way down into the earths crust in the form of hydrocarbons, calcium carbonate and other carbon-containing molecules. Eventually these materials will complete the cycle and emerge from a volcano again.

Human-caused greenhouse gas emissions are also derived mainly from the hydrocarbons left behind by prehistoric plants and animals but the process is much more accelerated. The problem with anthropogenic greenhouse gas emissions is that carbon is moved from the crust to the atmosphere at a much faster rate that greenhouse gasses are moved back to the crust.

Do Volcanoes Cause Global Cooling?In addition to the greenhouse gasses that are emitted by volcanoes there are massive amounts of other gasses and particulate emissions. These gasses and particulates have caused short-term "ice ages," beautiful sunsets, and the recent halt of air travel across a large part of Europe. Sulfur Dioxide (SO2) turns into sulfuric acid, which reflects sunlight, as do particulates of glass and other materials. These cooling effects only last as long as the particulates and gasses stay in the atmosphere, which is not more than a few years. Cooling effects from volcanoes may help to temporarily keep global temperatures down but they do nothing to lessen the CO2 concentrations in the atmosphere and the many issues caused by that, including ocean acidification.

While many lives have been disrupted by this most recent volcanic eruption, the environmental impact may be positive overall, especially if you consider how many flights have been avoided and how many people opted to take the train instead. Global air travel emissions are exceeding 600 million metric tonnes of CO2 annually. If we assume that air travel to/from/in Europe represents 1/5 of global air travel, then the 5 days (so far) of flight cancellations could have prevented 1.5 million metric tons of greenhouse gas emissions. This is probably no consolation to affected travelers but it is interesting to think that the greenhouse gas emissions from the volcanic eruption in Iceland are being offset by the reduction in air travel.